<button id="btn" class="btnClass">获取event对象</button>
<script>
var btn=document.getElementById('btn');
btn.onclick=function(e){
    var obj=event.target||window.event.srcElement;
    console.log(obj.nodeName);
    console.log(obj.id);
    console.log(obj.className);
    console.log(obj.innerText);
}
</script>